As a method of manufacturing a gear by skiving, according to Patent Document 1, an annular-disc like work is supported to be rotatable about a rotational axis. There is provided a pinion type cutter supported to be rotatable about a rotational axis different from the rotational axis of the work. And, the work and the cutter are driven in synchronism. In this method, as the cutter is moved along a direction of tooth trace of the gear, the work is cut by the cutter to manufacture an internal gear.